The amount of data flowing over networks has increased dramatically recently due to various network service enhancements. Accordingly, in order to promote the usage efficiency of network bandwidth, link aggregation (LAG), which is a technology for using a plurality of physical lines as one logical line, has been standardized as IEEE 802.3ad.
On the other hand, improvements in communication speeds and processing speeds have also advanced in data transmission devices. Data transmission devices are now able to quickly process large amounts of data due to these improvements. Data transmission devices are expected to accommodate long frames, which handle a large amount of data in one frame, in order to quickly process the huge amounts of data that flow through the networks. In particular, a frame that exceeds 9000 bytes is called a jumbo frame.
When short and long frames are used in one network, short frames are made to wait for processing while long frames that flow into the network are processed. As a result, processing of short frames is delayed and there is a risk that delay fluctuations may occur. For example, when the delay fluctuations occur, the arrival times of short frames at a computer that processes short frames may become varied and it is conceivable that the reception order of the short frames may be changed in the computer. The computer that receives the short frames may not be able to perform processing accurately when the order of the received short frames is changed in this way. For example, IP telephone is a service that uses short frames and requires minimal delays. Thus, when a service such as IP telephone and a service that uses jumbo frames co-exist in one network, there is a possibility that delay fluctuations of IP telephone frames may occur due to the jumbo frames. In this case, the IP telephone service may become delayed.
Japanese Laid-open Patent Publication No. 2005-303516 discusses, as a technology for these types of long frames, a technology for performing fragmentation by fragmenting long frames into a certain size at the transmission source and rebuilding the long frames at the receiving side. Moreover, Japanese Laid-open Patent Publication No. 9-312668 discusses a technology for configuring a LAG and sorting output packets to physical lines that configure the LAG in accordance with the packet sizes, so as to increase the ratio of reading short packets.